arah2/.planning/quick/261026-d95-alt-direction-split-isolated-research-si/261026-d95-SUMMARY.md

phase, plan, subsystem, tags, requires, provides, affects, tech-stack, key-files, decisions, metrics

phase	plan	subsystem	tags	requires	provides	affects	tech-stack	key-files	decisions	metrics
quick	261026-d95	routing	ALT bidirectional directional oracle benchmark	ARG2 landmark tables shipped routeAstar	proved pair-domain ALT isolated research runner NO-GO verdict		added patterns pair-restricted landmark family selection independent A* frontier stop	created modified docs/ALT-DIRECTION-SPLIT-EXPERIMENT.md routing/scripts/experiment-alt-direction-split.mjs routing/test/alt-direction-split-experiment.test.mjs	Do not integrate candidate because paired p95 regresses despite reduced expansions	completed 2026-10-26

Quick Plan 261026-d95: Direction-split ALT isolated research summary

An independently consistent asymmetric ALT bound can be used on a query-restricted sentinel-free path domain with a conservative single-frontier A* stopping criterion, but this isolated implementation is NO-GO: p95 516.778 ms versus original shipped 118.923 ms on paired host measurements.

Tasks and commits

1. 57fd5ed — Proved P-1 and P-2 separately, including sentinel boundary and disconnected-path handling before writing experiment code.
2. 92fc213 — Added isolated experimental search and adversarial exhaustive Dijkstra-oracle tests (no production imports).
3. 9a671bd — Added seeded real-graph oracle, paired original/clone measurement, expansion instrumentation, and recorded exact results/NO-GO in the experiment document.

Validation and verdict

• New and existing routing suite: 85 passed, 0 failed, including unchanged shipped A1/625. Typecheck passed.
• Fixed-seed 200-pair real graph: 182 routes, 18 unreachable, 120 rejected snap probes, zero suboptimal, oracle-mismatch or class-break cases.
• Extended paired workload: 53 routed/100 drawn, 41 snap misses, 6 unreachable. Two alternate-order rounds. Experiment/isolated shipped clone expansions 0.709×; experiment/original shipped p95 4.35× slower. Original shipped p95 118.923 ms; experimental p95 516.778 ms.
• D-03 unchanged frozen gate passed. Shipped extended CPU gate FAILED at p95 127.933 ms > 8 ms. Representative free-plan Worker CPU: NOT MEASURED.
• Full provenance and proof details: docs/ALT-DIRECTION-SPLIT-EXPERIMENT.md. Neither this branch nor the read-only binary symlink was deployed or merged.

Deviations from Plan

[Rule 3 - Blocking] Local node_modules was initially absent (L2 bundle marker failed and tsc was unavailable); ran npm ci --ignore-scripts --no-audit --no-fund, then tests and typecheck passed. No lockfile changes.

[Rule 1 - Bug] The initial diagnostic assertion reversed the backward edge inequality in code; corrected to compare the reverse search's h_b(v)-h_b(u) on v→u. Initial run failed loud on a real edge; rerun passed the 200-pair oracle and new tests.

[Rule 2 - Measurement completeness] The shipped search does not export expansion counters. Created and automatically removed a source-identical temporary clone with settled counters injected and measured the unmodified original separately; compared every route's seconds across the two controls. No production file modified.

Known Stubs

None in the search. Shipped-original settled expansions are deliberately NOT MEASURED directly; the source-identical instrumented clone supplies an explicitly labeled proxy rather than fabricated numbers. Worker-host CPU remains NOT MEASURED.

Self-Check: PASSED

Verified all three experiment files exist, commits 57fd5ed, 92fc213, 9a671bd exist, branch is research/alt-direction-split, and protected production/baseline/roadmap files differ neither from ceb71c2 nor this task's commits.